1. Field of the Invention
The present invention relates to a linear compressor adapted to compress fluid, such as refrigerant gas, and more particularly to a linear compressor in which a high or low pressure is produced in a space between a cylinder and a piston upon reciprocation of the piston to enable oil to be supplied into the space between the cylinder and the piston.
2. Description of the Related Art
Generally, linear compressors are machines used to suction and compress fluid, such as refrigerant gas, and discharge the compressed fluid as a piston rectilinearly reciprocates inside a cylinder by making use of driving power of a linear motor.
FIG. 1 is a sectional view illustrating a conventional linear compressor.
As shown in FIG. 1, the conventional linear compressor comprises a shell 2, a liner compressing unit 10, and an oil pump 20. The shell 2 receives oil O in a bottom region thereof, and the linear compressing unit 10 is disposed in the shell 2 to vibrate under operation of a damper 8. The linear compressing unit 10 serves to suction and compress fluid and discharge the compressed fluid. The oil pump 20, located below the linear compressing unit 10, is adapted to pump the oil O received in the bottom region of the shell 2 into the linear compressing unit 10 upon vibration of the linear compressing unit 10.
A fluid suction pipe 3 and a fluid discharge pipe 4 pass into the shell 2, and the fluid discharge pipe 4 is also connected to the linear compressing unit 10. In this way, the fluid is suctioned into the shell 2 via the suction pipe 3, and then is discharged via the discharge pipe 4 after being compressed in the linear compressing unit 10.
The linear compressing unit 10 comprises a cylinder block 16 provided with a cylinder 12, a back cover 24 provided with a fluid suction pipe 22, and a piston 30 rectilinearly reciprocably disposed inside the cylinder 12. The piston 30 internally defines a fluid suction channel 28 for allowing the fluid to be suctioned into the cylinder 12. The linear compressing unit 10 further comprises a fluid suction valve 32 installed in the piston 30 to open or close the fluid suction channel 28, a linear motor 34 for rectilinearly reciprocating the piston 30, and a discharge valve assembly 36 provided to open or close a front end of the cylinder 12. To the discharge valve assembly 36 of the linear compressing unit 10 is connected the fluid discharge pipe 4.
In addition, for the lubrication/cooling of the cylinder 12 and the piston 30, the linear compressing unit 10 comprises an oil suction channel 37 and an oil discharge channel 38.
The oil suction channel 37 is a combination of an oil pipe 39, an oil cover 41, a cylinder block suction channel 42, and a cylinder suction channel 43. The oil pipe 39 is immersed at an end thereof in the oil O received in the bottom region of the shell 2. The oil cover 41 is coupled to the cylinder block 16 to define an oil passage 40 therebetween. The cylinder block suction channel 42 serves to guide the oil from the oil passage 40 through the cylinder block 16, and the cylinder suction channel 43 serves to supply the oil from the cylinder block suction channel 42 to a space defined between the cylinder 12 and the piston 30.
The oil pump 20 comprises an oil cylinder 44, an oil piston 45, and front and rear oil springs 46 and 47. The oil cylinder 44 is mounted below the linear compressing unit 10 to communicate with the oil suction channel 37, more particularly, to the oil passage 40. The oil piston 45 is rectilinearly reciprocably disposed inside the oil cylinder 44, and the oil springs 46 and 47 are positioned at opposite sides of the oil piston 45 inside the oil cylinder 41 to elastically support the oil piston 45.
Reference numeral 48 denotes an oil suction valve, which operates by a pressure difference between the oil pipe 39 and the oil passage 40 to open or close an entrance of the oil passage 40. Reference numeral 49 denotes an oil discharge valve, which operates by a pressure difference between the oil passage 40 and the cylinder block suction channel 42 to open or close an exit of the oil passage 40.
In the conventional linear compressor configured as stated above, the oil piston 45 of the oil pump 20 vibrates as the linear compressing unit 10 vibrates.
When the oil piston 45 moves backward, a low pressure is produced in the oil passage 40 to open the oil suction valve 48, thereby causing the oil O to be suctioned via the oil pipe 39 and filled in the oil passage 40.
On the other hand, when the oil piston 45 moves forward, a high pressure is produced in the oil passage 40 to open the oil discharge valve 49, thereby causing the oil O, filled in the oil passage 40, to pass, in sequence, the cylinder block suction channel 42 and the cylinder suction channel 43, and to be supplied into the space between the cylinder 12 and the piston 30.
The supplied oil between the cylinder 12 and the piston 30 is used to lubricate/cool the cylinder 12 and the piston 30, and then is discharged to the outside of the linear compressing unit 10 via the oil discharge channel 38. The discharged oil is again collected in the bottom region of the shell 2.
However, the above described conventional linear compressor has a problem in that it requires a number of oil pumping elements including the oil cylinder 44, the oil piston 45, and the front and rear oil springs 46 and 47, resulting in a complicated pumping structure and high cost.
Further, as a result of positioning the oil cylinder 44, the oil piston 45, and the front and rear oil springs 46 and 47 below the linear compressing unit 10, it is impossible to arrange terminals of the linear motor 34 below the linear compressing unit 10. This significantly restricts space utility of the linear compressor.